[Freeswitch-users] Better results from mod_vmd

[Eric des Courtis]

Matt,

Okay the good news is vmd should be able to handle these cases. The
bad news is for whatever reason they are not getting detected at the
moment.

vmd-not-panasonic-home-ans.wav is a sine at ~1400Hz you can change
MAX_FREQ to 1450 and play with MIN_AMPL if that still doesn't help.

The following seem to use the same beep:

vmd-not-tmobile.wav is a sine at ~750Hz but has a bit of noise
vmd-not-sprint.wav is a sine at ~750Hz but has a bit of noise
vmd-not-sprint.wav is a sine at ~750Hz but has a bit of noise

You can try to play with these values:

POINTS 32
VALID 22
MAX_CHIRP 22

If that doesn't work let me know I will try to improve the algorithm
to detect the providers.

Cheers!

Eric des Courtis



On Mon, Aug 17, 2009 at 1:52 PM, Matthew Fong<mattdfong at gmail.com> wrote:
> Hi Eric,
> Thanks for the response. I had tried emailing you @brenbria.com and the
> email had bounced, thanks for responding to my mail.
> If you'd be interested I .zipped up my sample voicemail beeps
> at http://bandcon.hellohunter.com/vmd_wav.zip
> I'm relatively new to telephony, but can you point me in the right direction
> for figuring out if the beeps are sinewaves. About as far as I've come with
> audio is being able to open the .wav files in audacity. Any website
>  recommendations I can read? Thanks so much.
> --matt
>
> On Mon, Aug 17, 2009 at 10:29 AM, Eric des Courtis
> <eric.des.courtis at gmail.com> wrote:
>>
>> Matt,
>>
>> You must first capture the audio beeps and verify that they are sine
>> waves. If not, simply tweaking the algorithm will not give you better
>> results.
>>
>> It might be possible to use FFT and I would be happy to help you
>> implement such a solution but keep in mind FFT is very very demanding
>> on the hardware. Ideally what you want to find out is what functions
>> was use to generate the beep in the first place so that it can be
>> detected. Is it two sines waves like in DTMF? Or something more
>> complex?
>>
>> Anyway my email is eric.des.courtis at benbria.ca.
>>
>> Cheers.
>>
>> Eric des Courtis
>>
>> On Mon, Aug 17, 2009 at 12:26 AM, Matthew Fong<mattdfong at gmail.com> wrote:
>> > I tried emailed Eric, seeking advice on this, but his email (the one in
>> > the
>> > source code) is bouncing email (invalid user), so thought I would ask
>> > here
>> > instead. If anyone has eric's new email address, I'd be interesting in
>> > it.
>> >
>> > I did some tests with mod_vmd this afternoon, but I'm only finding about
>> > 33%
>> > of the voice mail beeps and did have 1 false-positive in my test of
>> > 7 voice
>> > mail machines. I've recorded the audio of the session in .wav files that
>> > were both successful and not, as a comparison. I can upload the .wav
>> > files
>> > if they would be useful.
>> > mod_vmd works great for voicemails of Skype Users, and kall8.com, but
>> > has
>> > issues dealing with mobile phone carriers.
>> > sprint - not successful
>> > tmobile - not successful
>> > verizon - not successful
>> > panasonic home answering machine system - not successful
>> > kall8 - SUCCESS
>> > skype - SUCCESS
>> > I'm wondering if you can recommend a simple fix, like changing some of
>> > the
>> > constants like MAX_FREQ, or MIN_TIME at the top of the mod_vmd.c source
>> > file, or if better success requires more complex analysis.  Do you have
>> > any
>> > recommendations on how this might be done? Listening to the .wav's
>> > its apparent the beeps are not as loud for the mobile phone carriers as
>> > they
>> > are with skype and kall8. Any guidance would be greatly appreciated.
>> > --matt
>> > hello hunter
>> > http://www.hellohunter.com
>> > voice broadcasting & hosted dialer
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>
>